In the case of vehicle transmissions, the oiling of gears and bearings is of particular significance. Sufficient oiling should be ensured, and the amount of oil required for lubrication and cooling should be kept as low as possible. From the prior art it is known to utilize different oil pumps, hollow shafts, and oil lines for oiling. It is also known to utilize oil dams, oil ducts, and/or elevated oil levels in the transmission.
DE 41 17 409 A1, for example, describes a shaft having a central axial bore and a multitude of radial bores opening into this central bore, in the case of which lubricant from one shaft end of the hollow shaft is introduced into the central bore in the form of a longitudinal duct and this lubricant is transferred via the radial bores, in the form of radial ducts, to components arranged outside the hollow shaft. In this case, it is provided that a hollow adapter sleeve is inserted into at least that radial bore that is situated closest to the open shaft end of the hollow shaft and projects, via its end facing the hollow-shaft central axis, beyond the circumferential surface of the central bore, i.e., extends beyond the circumferential surface of the central bore into the central bore. This measure causes a hindrance to the lubricant outflow at this radial duct, and therefore the lubricant, which has been axially introduced into the central bore and, as is known, does not reach the rotational speed or the circumferential speed of the hollow shaft quickly enough, no longer flows out to an increased extent at this radial bore situated closest to the inflow point. Further radial ducts can also be formed so as to overhang into the longitudinal duct, wherein it is advantageous for a uniform distribution of lubricant when the overhang is designed to decrease starting from the open shaft end.
DE 10 2005 052 449 A1 describes a further shaft having a central axial bore and a multitude of radial bores opening into this central bore, in the case of which lubricant from one shaft end of the hollow shaft is introduced into the central bore in the form of a longitudinal duct and this lubricant is transferred via the radial bores, in the form of radial ducts, to components arranged outside the hollow shaft. In order to avoid the situation in which too much oil exits from the radial bores of the internally oiled hollow shaft, which can occur, for example, when the oil level in the shaft rises sharply, an insert tube is inserted into each of the radial bores in order to adjust the flow discharged via the radial bores, the insert tube extending beyond the circumferential surface of the central bore into the central bore. In this way, the flow that is flowing out via the particular insert tube can be adjusted by way of the distance of the end of this insert tube facing the center of the hollow shaft to the oil level which is becoming established, under speed, in the central bore of the hollow shaft. In addition, at least one small radial bore can be provided in the insert tube, in order to materialize, in this way, a further possibility for controlling or adjusting the flow.